Field of the Invention
The present invention relates to an electron microscope and an image acquisition method.
Description of Related Art
A scanning transmission electron microscope (STEM) is an instrument for obtaining a scanning transmission electron microscope (STEM) image by scanning a focused electron beam (electron probe) over a sample and detecting electrons transmitted through the sample (see, for example, JP-A-2012-22971).
One proposed measurement method using a scanning transmission electron microscope consists of scanning a conically focused electron beam over a sample, recording a convergent beam electron diffraction pattern for each pixel by an imager in synchronism with the scanning, and obtaining plural convergent beam electron diffraction patterns having a one-to-one correspondence with positions on the sample.
In order to achieve this measurement method, however, plural convergent beam electron diffraction patterns must be recorded in synchronism with the scanning of the electron beam. This needs an imager which records images (convergent beam electron diffraction patterns) at high speed. If the image recording time is lengthened, the instrument will be more affected by external disturbances and sample drifts due to temperature variations. Therefore, it is desired to shorten the image recording time as much as possible.